Stink Bugs Congregating on Your House

Image from Oregon State Extension

It is not your imagination, the brown marmorated stink bug officially known as Halyomorpha halys is trying to get into your house. The large bug appears to be almost waiting for you to open your garage or any other door to slip into the house. The adult stink bugs congregate in early fall in the afternoon waning sun and seek sites to spend the winter especially inside buildings. The stink bugs will occasionally reappear during warmer sunny periods throughout the winter, and then as it emerges in the spring to mate. The stink bug is not harmful to people, houses, or pets, they do not bite, sting, suck blood or carry disease. They do not eat wood or bore into it so they do not damage your house, but they are large bugs, a little less than ¾ of an inch, can fly and are seemingly relentless.

The stink bugs are not native to the United States they arrived from China in the late 1990’s or around 2000 when they were first noted in Pennsylvania. In the United States they do not yet have any natural enemies and they have spread widely in the Mid-Atlantic States causing crop damage. In its native range of China, Japan, Korea it is known as an agricultural pest and has become a serious threat to the fruit, vegetables and farm crops of the Mid-Atlantic region here and is still spreading to other regions of the United States. Pesticides have very limited effect on the bugs. The economic damage that the shield shaped bugs are causing the United States Department of Agriculture, USDA, and the Land Grant Universities to study and research a solution. Studies are now underway at the USDA’s Biological Control Research laboratory to develop a biological control using egg parasites. However, that is not going to help with the invasion of your home.

Exterior applications of insecticides may offer some very short lived relief from infestations. A synthetic pyrethroid (i.e. deltamethrin, cyfluthrin, lambda-cyhalothrin, cypermethrin, sumithrin or tralomethrin) are reported by the USDA to have some effectiveness on stink bugs. Unfortunately, because these insecticides are broken down by sunlight and the effectiveness of the treatment will not last more than a few days or up to a week. Although using an insecticidal dust treatments to voids where stink bugs emerge from may kill hundreds of bugs, there is the possibility that carpet beetles will feed on the dead stink bugs and create a larger problem. Carpet beetles attack woolens, stored dry goods or other natural products in the home. By using the insecticidal dust you may add a carpet beetle problem to the stink bug invasion. Although aerosol type pyrethrum foggers will kill stink bugs that have amassed on ceilings and walls in living areas, it will not prevent more stink bugs from emerging shortly after the room is aired out.

Mechanical exclusion is the best method to keep stink bugs out of your house. If the bugs get into your home they have been reported to emerge from behind baseboards, around windows and doors and around exhaust fans, dryer vents or ceiling fans and lights in massive swarms. The degree of invasion into your home depends on how well you have sealed your house. The bugs are good flyers and once inside their ability to launch in a dive bomb move when disturbed is a bit scary. Pesticides are generally ineffective against stink bugs. The only way to deal with them is mechanical- keep them out and I kid you not vacuum them up if they get in. WARNING: the stink bugs get their nickname from the unpleasant order they emit if squished or annoyed and be aware that the vacuum will acquire the pungent and unpleasant smell of the stink bugs for a period of time. If the bugs get into the house vacuum them up with a shop vacuum or an old vacuum cleaner. The smell will go away quickly. Dump the bugs into a bucket of soapy water to die.

The same techniques that keep mice from entering the home and seal your home rigorously from the elements will keep most stink bugs from entering your home. First of all, there is no way to prevent stink bugs from getting into the garage because garage doors just do not seal that tight in their tracks. Instead, it is necessary to sweep the bug out of the garage in the cold mornings when they are inactive and seal all entries to the house. Steel wool and lath screening should be pushed into every crack; the area caulked with an all-weather caulk and sealed using spray insulation. New weather stripping should be placed on every exterior door. All the kitchen pipes, the dryer vent pipe, the gas pipe to the fireplace the pilot light and valve to the fireplace should be fitted with lath screening. The space between the foundation and siding should be carefully caulked and sealed. Attic vents should be screened. Windows should be caulked and weather stripping on the windows checked. All exterior holes for electrical, plumbing, and gas lines should be carefully sealed with Duxseal. This will keep not only the stink bugs out of the house but prevent invasion of mice.